Pervious Concrete Pavement is a water management system.
Its bottom component is a soil base that will let water percolate through it to the aquifer below. This includes sandy and gravely soils. A layer of clay may require a system to allow water to seep through to the aquifer below which could include pipes, French drains or removing some clay. A capable site engineer’s services are a valuable tool at this time. Below is a picture of a typical well draining soil.
When such soil is not available, some times a crushed concrete or aggregate base is installed to store water under the pervious concrete paving. This allows the filtered water to slowly pass through the less cooperative soils by capillary seepage.
Aggregate Base under Pervious Concrete being poured. In this case the aggregate prevents a build up of water in the pervious. This is extremely important during freeze-thaw conditions.
For the system to function properly the correctly designed mixture must be loaded properly at the ready-mix plant, delivered promptly by a truck driver who is thoroughly trained in working with pervious ready-mix, and willing to thoroughly cooperate with the installation crew overseer.
As the trucks arrive to discharge the pervious concrete, they should be accommodated by a properly leveled base set to correct elevations and thoroughly compacted. No deep ruts should be created by the truck tires.
Placing and finishing requires a trained crew interacting like clockwork. Each member knows where he or she should be to implement an expeditious and expert installation.
This combination of a properly designed site, experienced Pervious Concrete Crews, the properly measured and mixed materials, and the right methods are what makes Pervious Concrete a Green Material, a rain water management tool that will perform well with minimum maintenance for many decades!